自己写的 分页标签

Pager这个类是用来装载分页信息的.如当前是第几页,每一页有多少数据等等

package org.jksoft.pager;

public class Pager {

	/**
	 * 用来控制分页信息.
	 * @author jackey
	 * 
	 */
	private int currentPage;// 当前第几页
	private int totalRows; // 一共有多少行数据
	private int totalPages;// 总页数
	private int pageSize = 10; // 一页有多少数据,默认为10

	private boolean hasNext;// 是否有下一页
	private boolean hasPrevious;// 是否有前一页
	private boolean isLast;// 当前页 是否是最后一页

	public Pager() {
		this.currentPage = 1; // 初始化为第一页
	}

	public void init(int totalRows, int pageSize) {
		if (pageSize != 0) { // 如果传过来的参数不为0才赋值,否则使用默认值
			this.pageSize = pageSize;
		}
		if (totalRows != -1)//-1表示不传参数,只是调用init方法.
			this.totalRows = totalRows;

		this.hasPrevious = false;// 无上一页
		if (this.totalRows % this.pageSize == 0) {
			this.totalPages = this.totalRows / this.pageSize;
		} else {
			this.totalPages = this.totalRows / this.pageSize + 1;
		}// 计算页数

		refresh();

	}

	/**
	 * 根据参数判断是否有上一页,下一页,尾页等等.
	 * 刷新用.
	 * @author jackey
	 */
	public void refresh() {
		if (currentPage == 1) {
			this.hasPrevious = false;
		}
		if (currentPage > 1) {// 当前页大于1,有上一页,首页
			this.hasPrevious = true;
		}
		if (this.totalPages > this.currentPage) {// 如果页数大于当前页 则有下一页 和尾页
			this.hasNext = true;
			this.isLast = false;
		}
		if (this.totalPages == this.currentPage) {// 如果总页数等于当前页,那么是最后一页
			this.isLast = true;
			this.hasNext = false;
		}
		if (this.totalPages < this.currentPage) {// 如果当前页
			return;
		}
	}
	//是否首页
	public boolean isFirstPage(){
		if(this.currentPage == 1){
			return true;
		}
		return false;
	}
	//是否最后一页.
	public boolean isLastPage(){
		if(this.isLast){
			return true;
		}
		return false;
	}

	//首页,当前页码 = 1
	public void first(){
		this.currentPage = 1;
		refresh();
	}
	//下一页,当前页码 + 1;
	public void next(){
		this.currentPage += 1;
		if(this.currentPage >= this.totalPages){
			this.currentPage = this.totalPages;
		}
		refresh();
	}
	//上一页,当前页码 - 1
	public void previous(){
		this.currentPage -= 1;
		if(this.currentPage <= 0){
			this.currentPage = 1;
		}
		refresh();
	}
	//尾页,当前页码等于总页数
	public void last(){
		this.currentPage = this.totalPages;
		refresh();
	}

	public int getCurrentPage() {
		return currentPage;
	}
	//设置了当前页后要修改参数.
	public void setCurrentPage(int currentPage) {
		this.currentPage = currentPage;
		refresh();
	}
	//获取总行数 .
	public int getTotalRows() {
		return totalRows;
	}
	//修改总行数,要重新计算总页数,以及其他参数.
	public void setTotalRows(int totalRows) {
		this.init(totalRows, 0);
	}
	//获取总页数
	public int getTotalPages() {
		return totalPages;
	}
	//获得页大小
	public int getPageSize() {
		return pageSize;
	}
	//获得 "是否 有下一页"
	public boolean isHasNext() {
		return this.hasNext;
	}
	//获得是否有上一页
	public boolean isHasPrevious() {
		return this.hasPrevious;
	}
	//是否最后一页.
	public boolean isIsLast() {
		return this.isLast;
	}

}

------------------------------------------------------------------
PagerHelp是用来从session中取Pager的.如果没有则new一个.

package org.jksoft.pager;

import javax.servlet.http.HttpServletRequest;

public class PagerHelp {

	public static Pager getPager(HttpServletRequest request, int totalRows,
			int pageSize) {
		Pager pager = null;
		Object obj=  request.getSession().getAttribute("_pager");
		if (obj == null) {
			pager = new Pager();
			pager.init(totalRows, pageSize);
		}else
			pager = (Pager)obj;
		String page = "";//request.getParameter("page");
//		page = page.trim().toLowerCase();
		if (page == null || "".equals(page) || "first".equals(page)) {
			pager.first();

		} else if ("previous".equals(page)) {
			pager.previous();

		} else if ("next".equals(page)) {
			pager.next();
		} else if ("last".equals(page)) {
			pager.last();
		}
		return pager;

	}
}

PagerTag用来显示标签.

package org.jksoft.pager;

import java.io.IOException;
import java.util.Enumeration;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.jsp.JspException;
import javax.servlet.jsp.JspWriter;
import javax.servlet.jsp.tagext.BodyContent;
import javax.servlet.jsp.tagext.BodyTagSupport;

public class PagerTag extends BodyTagSupport {

	String url;
	String page;
	Pager pager;
	String forward;
	int total;
	int size;

	public int doStartTag() throws JspException {
		HttpServletRequest request = (HttpServletRequest) pageContext
				.getRequest();

		System.out.println(total + " --------- " + size);
		// 取pager.保存分页信息的类.
		pager = PagerHelp.getPager(request, total, size);
		// out对象
		JspWriter out = pageContext.getOut();
		pager.setCurrentPage(6);

		try {
			out.println("<style type='text/css'>" + "<!--"
					+ "a:link { text-decoration: none;color: blue}"
					+ "a:active { text-decoration:blink}"
					+ "a:hover { text-decoration:underline;color: red}"
					+ "a:visited { text-decoration: none;color: green}" + "-->"
					+ "</style>");
			if (pager.isHasNext() && pager.isHasPrevious()) {
				// 中间某页
				System.out.println("if");
				out.println("<a href='" + forward + "' page='first'>首页</a>");
				out.println("<a href='" + forward + "' page='next'>下一页</a>");
				out
						.println("<a href='" + forward
								+ "' page='previous'>上一页</a>");
				out.println("<a href='" + forward + "' page='last'>尾页</a>");
			} else if (pager.isFirstPage() && pager.isHasNext()) {
				// 首页,有下一页
				System.out.println("else if 1");
				out.println("<a href='#' page='first'>首页</a>");
				out.println("<a href='" + forward + "' page='next'>下一页</a>");
				out.println("<a href='#' page='previous'>上一页</a>");
				out.println("<a href='" + forward + "' page='last'>尾页</a>");
			} else if (pager.isHasPrevious() && pager.isIsLast()) {
				// 最后一页有上一页
				System.out.println("else if 2");
				out.println("<a href='" + forward + "' page='first'>首页</a>");
				out.println("<a href='#' page='next'>下一页</a>");
				out
						.println("<a href='" + forward
								+ "' page='previous'>上一页</a>");
				out.println("<a href='#' page='last'>尾页</a>");
			} else {
				System.out.println("else");
				out.println("<a href='#' page='first'>首页</a>");
				out.println("<a href='#' page='next'>下一页</a>");
				out.println("<a href='#' page='previous'>上一页</a>");
				out.println("<a href='#' page='last'>尾页</a>");

			}
			out.println("<font color='green'>  共有  " + pager.getTotalRows()
					+ "  条数据  当前第 "
					+ pager.getCurrentPage() + "页 / 共  "
					+ pager.getTotalPages() + "  页</font>");

		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		request.getSession().setAttribute("_pager", pager);
		return EVAL_BODY_INCLUDE;
	}

	public int doAfterBody() throws JspException {

		return SKIP_BODY;
	}

	public int doEndTag() throws JspException {
		return SKIP_PAGE;
	}

	public void doInitBody() throws JspException {
		super.doInitBody();
	}

	public void setBodyContent(BodyContent b) {
		// TODO Auto-generated method stub
		super.setBodyContent(b);
	}

	public int getTotal() {
		return total;
	}

	public void setTotal(int total) {
		this.total = total;
	}

	public int getSize() {
		return size;
	}

	public void setSize(int size) {
		this.size = size;
	}

}

-------------------------------------------------------------------
编写tld文件,

<?xml version = "1.0" encoding = "utf-8" ?>
<taglib version="2.0"
   xmlns = "http://java.sun.com/xml/ns/j2ee"
   xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
   xmlns:shcemalocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd">
   <description>自定义标签</description>
   <display-name>JSTL core</display-name>
   <tlib-version>1.1</tlib-version>
   <short-name>firstLabel</short-name>
   <uri>http://java.sun.com/jsp/jstl/core</uri>

 <tag>
 	<name>LittlePager</name>
 	<tag-class>org.jksoft.pager.PagerTag</tag-class>
 	<body-content>JSP</body-content>
 	 <attribute>
   		<name>total</name>
   		<required>true</required>
   		<rtexprvalue>true</rtexprvalue>
   </attribute>
    <attribute>
   		<name>size</name>
   		<required>true</required>
   		<rtexprvalue>true</rtexprvalue>
   </attribute>
 </tag>

</taglib>

--------------------------------------------------------------
在页面里
<%@taglib uri="/WEB-INF/pager.tld" prefix = "pager" %>
<pager:LittlePager total="100" size="5"></pager:LittlePager>
引入标签并使用就可以了.

可能有许多地方不正确,欢迎指正